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A290599 Number of numbers from 1 to A002808(n) - 1 that are non-coprime to A002808(n). 3
1, 3, 3, 2, 5, 7, 7, 6, 7, 11, 11, 8, 11, 15, 4, 13, 8, 15, 21, 15, 12, 17, 10, 23, 19, 14, 23, 29, 23, 20, 23, 31, 6, 29, 18, 27, 35, 14, 31, 20, 29, 43, 31, 26, 31, 16, 45, 35, 24, 45 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) gives the row length of the irregular triangle A290600.

LINKS

Table of n, a(n) for n=1..50.

FORMULA

a(n) = number of positive numbers k < A002808(n) with gcd(A002808(n), k) not 1.

EXAMPLE

a(4) = 2 because A002808(4) = 9, with the two non-coprime positive numbers smaller than 9, namely 3 and 6. See row n = 4 of A290600.

CROSSREFS

Cf. A002808, A290600.

Sequence in context: A265751 A143050 A214919 * A070163 A083343 A292527

Adjacent sequences:  A290596 A290597 A290598 * A290600 A290601 A290602

KEYWORD

nonn

AUTHOR

Wolfdieter Lang, Aug 30 2017

STATUS

approved

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Last modified October 16 13:24 EDT 2019. Contains 328084 sequences. (Running on oeis4.)